That's a thought. I'll look into it. I love the commander mode, although I wish units routed instead of fighting to the last man.
I should add that I also prefer single-player because I like the old school mount and blade single player campaigns where players recruited their force and interacted with NPCs. I think this could be done for ACW, especially if one limited the campaign to a single region like Missouri-Eastern Kansas-North Arkansas, or perhaps Virginia-Maryland-Pennsylvania. Players could recruit a force (which is historical) and interact with other officers. Instead of being awarded a castle or city a character could be promoted or earn some special weapon or something. I think that would be fun and add some context to the battles.
Just my 2 cents.